Last year, when Ruth Mackenzie was appointed director of the Cultural Olympiad, the very concept was at a low ebb. No one seemed to know exactly what it meant. The early planning seemed bogged down in impenetrable jargon about Olympic "themes" and dead phrases such as "celebrating youth and diversity". While worthy, these had the kind of committee-speak tang that is the enemy of good art. As one commentator put it, after attending the glossy, self-congratulatory launch in 2008, "it felt like we were all bathed in a warm vomit of inclusivity".

Mackenzie was the cavalry, brought in to give the Cultural Olympiad – which, should you still be in the dark, is the arts programme that will accompany the games, and which has been running, in various forms, since 2008 – a fresh start. She would have to be a sprinter: the opening ceremony might have been two years away, but that was still a hideously short time frame in which to pull together a coherent cultural programme for 2012. Mackenzie's appointment was greeted with relief, however: if anyone could pull it off, it was this former boss of Scottish Opera, Chichester Festival theatre and Manchester international festival. Like her or loathe her (and the arts world seems split, her nickname in some quarters being The Childcatcher, after the villain in Chitty Chitty Bang Bang), she is regarded as effective.

"Did I have time to spend two years doing research, which any director of any festival would expect?" she says crisply when we meet at the Department for Culture, Media and Sport. "No, I didn't. But there are merits in being decisive. There was no time to linger."

And in many ways – judging from the launch on Friday of her London 2012 festival – Mackenzie does seem to have pulled it off. The festival, running from 21 June to 9 September, will be the climax of the Cultural Olympiad. If all goes well, it will bring some much-needed focus to a rather inchoate programme that has risked lacking a binding identity.

To create the festival programme, Mackenzie and her team examined the work already in development, extracted the good stuff (such as Big Dance week, which saw 1.2 million people dancing in London last year) and quietly dropped the rest. She also opened her contacts book, inviting major international artists to make work that would form the high points of the festival; she cherrypicked projects being run by other institutions and drew them into the festival programme. For example, Tate Modern's regular Turbine Hall commission, which next year is by the Berlin-based artist Tino Sehgal, will be regarded as part of the festival.

The problem, perhaps, is that the definition is still somewhat baffling. The festival is not the same as the Cultural Olympiad – there are plenty of Cultural Olympiad events that will happen next summer that are not part of the festival. Nor is the festival, despite its title, a London thing: it will be UK-wide. Some events that are part of other festivals – such as the Southbank's festival of the world – will also be included in Mackenzie's London 2012 festival. Confused? Don't worry, says Mackenzie. London 2012 festival events will be identifiable through branding, a pink ribbon, that she says will give them the imprimatur of quality. "We encourage people to feel that if there is a pink ribbon on it, it's like a critics' pick: trust us, it's going to be amazing."

Wisely, she has ditched the idea of connecting the programme too closely to the sporting events. The only two Olympic "themes" she has dreamed up are the idea that the artists are "exceptional, gold-medal talents, capable of producing something that's a once-in-a-lifetime opportunity"; and the notion, as a loosely applied metaphor, of the Olympic truce, which in the ancient Greek Olympics was a downing of weapons between the frequently warring Hellenic nations for the duration of the games.

And so, bound together by Mackenzie's curatorship, the London 2012 festival does now have a certain coherence. It is recognisably her taste, whether originated by her or not. She has a bracing (and to my mind commendable) penchant for the European avant garde; there is serious work of all stripes; and contemporary music that is anything but lowest-common-denominator. So Birmingham will see the UK premiere of Jonathan Harvey's new epic choral work Weltethos, under Simon Rattle; there will be a strand devoted to the work of composer George Benjamin; Daniel Barenboim will bring the West-Eastern Divan Orchestra to the Proms; theatre-makers Deborah Warner and Fiona Shaw will create a series of installations on Britain's beaches; and there is the already announced Pina Bausch/Tanztheater Wuppertal retrospective planned for the Barbican in London.

Offsetting all that is more populist fare: David Hockney at London's Royal Academy, a celebration of Alan Ayckbourn in Scarborough and Chichester; and, presumably, the pop and comedy elements of the festival, which are to be announced next year. Skirting between the two extremes are some intriguingly eccentric works, such as Martin Creed's Work No 1197: All the Bells in a Country Rung As Quickly and As Loudly As Possible for Three Minutes. (Yes, Creed wants everyone in Britain to ring something – church bell, bike bell, doorbell – simultaneously to celebrate the opening of the Games.) Mackenzie hesitates to sum up the "tone" of the festivities but, if anything, she says, they will have a certain humour and wit: "There's something about the surprise and quirkiness of them – about being funny as well as touching."

Will the London 2012 festival feel like a festival? As Mackenzie herself says: "Most festivals are in fields or cities; this one is in an entire country." Good festivals involve audiences sharing a stream of thought or experiencing a sense of place. They create a feeling of "festiveness" and a certain camaraderie between audiences and artists. Mackenzie has worked to disperse London 2012 into all parts of Britain, from Shetland to Cardiff, from Enniskillen to Gateshead to Margate. But that geographic generosity could cost her the coherence she wants, as most people are unlikely to get to any but a few events.

Mackenzie counters: "One of our offers is, we bring the events to you: we make sure there are amazing events all round the UK. You will feel a festive spirit in quite a few of our major cities. There is no doubt that there will be a critical mass of cultural events in London, and it's going to feel like it's absolutely at the centre of a festival – that goes for Edinburgh, Derry/Londonderry, Belfast, Birmingham, Stratford, too. What you can't do is have one festival club, you can't, and that's a sadness for us. Would it be easier if it was all in one city? Yes. But if we're to offer 10m free tickets or free places at events – well, you just couldn't do that in one city."

Krapp's Last Tape in Enniskillen

And what – to use a dreaded piece of Olympics jargon – does Mackenzie want the legacy to be? It's partly, she says, about using the strength and power of the Olympic brand to tempt audiences to take a punt on events they wouldn't normally go for. "I don't want to sound pious, but I believe in the quality of these artists. I believe that if you have the chance to see David Hockney or Robert Wilson's Krapp's Last Tape in Enniskillen, I think you will be amazed. I really do. I think you'll remember it; I think it will shape the way you think."

There are more tangible ends in view: the government, for example, has set targets for increasing cultural tourism to Britain once the games have finished. Mackenzie is also keen to raise the cultural stakes for subsequent Olympics, not least Rio in 2016. "If we are lucky, we will change the way future Olympics see their cultural festivals. I don't mind if Rio is better than us: I would like us to be the best yet, but I would be pleased if they were better than us."

The sheer scale of it all prompts more questions. At the latest count – and new projects are still being added – there were more than 1,000 events in the London 2012 festival, and many times that in the Cultural Olympiad as a whole from its 2008 inception. Will there be enough audiences to go round? And will 2013 be a terrible cultural letdown, arts organisations having exhausted their energy and budgets on big Olympic projects? One thing's for sure: far from there being nothing much to see next year, the UK is going to be awash with big ticket arts events. The danger, perhaps, is not cultural impoverishment – but cultural overdose.